Reaction of microglia and astrocytes in the rat brain cortex to free-electron laser irradiation

Reactions of microglia and astrocytes in the sensorimotor cortex of the rat resulting from a cortex tissue lesion made by a free-electron laser were studied with immunohistochemical techniques. Lipocortin-1 (LC1) was used its a microglia marker, while S100-beta glycoprotein was used to identify astrocytes. Three days after laser exposure, the quantity of LC1-positive microglial cells observed in the cortex along the edge of the laser lesion was 30% larger than that in the control There was no reaction of S100-beta-positive astrocytes observed within this time interval. Six days after laser exposure. the density of LC1-positive activated microglia along the edge of the laser Lesion further increased (210% of the above index), and the density of S100-beta-positive astrocytes also slightly increased (by 30% compared with the control). The data provide evidence that LC1-positive microglia. react to a laser-mode cortex injury more rapidly and intensively than astrocytes. It can be supposed that namely LC1 plays the role of an anti-inflammatory messenger in cortex microglial cells after laser exposure. In general, the pattern of microglia and astrocyte reactions is indicative of comparatively mild traumatization of the cortex tissue after laser irradiation.